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st: add a debug_flag module parameter request

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This patch adds a debug_flag parameter that can be set on module load, and allows the DEBUG facility without a module recompile.
Note that now DEBUG 1 is the default with this patch.

Usage: modprobe st debug_flag=1

Signed-off-by: Laurence Oberman <loberman@redhat.com>
Acked-by: Kai M??kisara <kai.makisara@kolumbus.fi>
Signed-off-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Laurence Oberman 2014-10-19 09:44:25 -04:00 committed by Christoph Hellwig
parent 26cf591e6d
commit 2bec708a88
2 changed files with 20 additions and 4 deletions
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8
Documentation/scsi/st.txt
View File

@ -506,9 +506,11 @@ user does not request data that far.)
DEBUGGING HINTS
To enable debugging messages, edit st.c and #define DEBUG 1. As seen
above, debugging can be switched off with an ioctl if debugging is
compiled into the driver. The debugging output is not voluminous.
Debugging code is now compiled in by default but debugging is turned off
with the kernel module parameter debug_flag defaulting to 0. Debugging
can still be switched on and off with an ioctl. To enable debug at
module load time add debug_flag=1 to the module load options, the
debugging output is not voluminous.
If the tape seems to hang, I would be very interested to hear where
the driver is waiting. With the command 'ps -l' you can see the state

16
drivers/scsi/st.c
View File

@ -56,7 +56,8 @@ static const char *verstr = "20101219";
/* The driver prints some debugging information on the console if DEBUG
is defined and non-zero. */
#define DEBUG 0
#define DEBUG 1
#define NO_DEBUG 0
#define ST_DEB_MSG KERN_NOTICE
#if DEBUG
@ -80,6 +81,7 @@ static int max_sg_segs;
static int try_direct_io = TRY_DIRECT_IO;
static int try_rdio = 1;
static int try_wdio = 1;
static int debug_flag;
static struct class st_sysfs_class;
static const struct attribute_group *st_dev_groups[];
@ -100,6 +102,9 @@ module_param_named(max_sg_segs, max_sg_segs, int, 0);
MODULE_PARM_DESC(max_sg_segs, "Maximum number of scatter/gather segments to use (256)");
module_param_named(try_direct_io, try_direct_io, int, 0);
MODULE_PARM_DESC(try_direct_io, "Try direct I/O between user buffer and tape drive (1)");
module_param_named(debug_flag, debug_flag, int, 0);
MODULE_PARM_DESC(debug_flag, "Enable DEBUG, same as setting debugging=1");
/* Extra parameters for testing */
module_param_named(try_rdio, try_rdio, int, 0);
@ -124,6 +129,9 @@ static struct st_dev_parm {
},
{
"try_direct_io", &try_direct_io
},
{
"debug_flag", &debug_flag
}
};
#endif
@ -4309,6 +4317,12 @@ static int __init init_st(void)
printk(KERN_INFO "st: Version %s, fixed bufsize %d, s/g segs %d\n",
verstr, st_fixed_buffer_size, st_max_sg_segs);
debugging = (debug_flag > 0) ? debug_flag : NO_DEBUG;
if (debugging) {
printk(KERN_INFO "st: Debugging enabled debug_flag = %d\n",
debugging);
}
err = class_register(&st_sysfs_class);
if (err) {
pr_err("Unable register sysfs class for SCSI tapes\n");